| Rob Pike | 69b74c3 | 2008-06-12 13:26:16 -0700 | [diff] [blame] | 1 | /* |
| 2 | http://code.google.com/p/inferno-os/source/browse/libbio/bgetc.c |
| 3 | |
| 4 | Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. |
| 5 | Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. |
| 6 | |
| 7 | Permission is hereby granted, free of charge, to any person obtaining a copy |
| 8 | of this software and associated documentation files (the "Software"), to deal |
| 9 | in the Software without restriction, including without limitation the rights |
| 10 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 11 | copies of the Software, and to permit persons to whom the Software is |
| 12 | furnished to do so, subject to the following conditions: |
| 13 | |
| 14 | The above copyright notice and this permission notice shall be included in |
| 15 | all copies or substantial portions of the Software. |
| 16 | |
| 17 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 18 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 19 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 20 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 21 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 22 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 23 | THE SOFTWARE. |
| 24 | */ |
| 25 | |
| 26 | #include <u.h> |
| 27 | #include <libc.h> |
| 28 | #include <bio.h> |
| 29 | |
| 30 | int |
| 31 | Bgetc(Biobuf *bp) |
| 32 | { |
| 33 | int i; |
| 34 | |
| 35 | loop: |
| 36 | i = bp->icount; |
| 37 | if(i != 0) { |
| 38 | bp->icount = i+1; |
| 39 | return bp->ebuf[i]; |
| 40 | } |
| 41 | if(bp->state != Bractive) { |
| 42 | if(bp->state == Bracteof) |
| 43 | bp->state = Bractive; |
| 44 | return Beof; |
| 45 | } |
| 46 | /* |
| 47 | * get next buffer, try to keep Bungetsize |
| 48 | * characters pre-catenated from the previous |
| 49 | * buffer to allow that many ungets. |
| 50 | */ |
| 51 | memmove(bp->bbuf-Bungetsize, bp->ebuf-Bungetsize, Bungetsize); |
| 52 | i = read(bp->fid, bp->bbuf, bp->bsize); |
| 53 | bp->gbuf = bp->bbuf; |
| 54 | if(i <= 0) { |
| 55 | bp->state = Bracteof; |
| 56 | if(i < 0) |
| 57 | bp->state = Binactive; |
| 58 | return Beof; |
| 59 | } |
| 60 | if(i < bp->bsize) { |
| 61 | memmove(bp->ebuf-i-Bungetsize, bp->bbuf-Bungetsize, i+Bungetsize); |
| 62 | bp->gbuf = bp->ebuf-i; |
| 63 | } |
| 64 | bp->icount = -i; |
| 65 | bp->offset += i; |
| 66 | goto loop; |
| 67 | } |
| 68 | |
| 69 | int |
| 70 | Bungetc(Biobuf *bp) |
| 71 | { |
| 72 | |
| 73 | if(bp->state == Bracteof) |
| 74 | bp->state = Bractive; |
| 75 | if(bp->state != Bractive) |
| 76 | return Beof; |
| 77 | bp->icount--; |
| 78 | return 1; |
| 79 | } |
